Before you choose a VoIP system, be sure to ask yourself these five essential questions.

2. Do you know what your WAN bandwidth usage is and what is running on it? Your VoIP system puts particular stress on wide-area links, so it is important to understand overall usage, particularly during peak times of day. “We have a metropolitan fiber loop with 10 megabits up and down to our offices here, so bandwidth isn’t an issue,” says Duncan Hill, a partner at the incubator Basecamp Partners in Toronto, which uses the Jazinga VoIP small business system.

“The main challenge with VoIP is understanding quality of service [QoS] issues,” says Bill Di Nardo, managing partner at Eventi Capital Partners, a Toronto-based venture capital firm. “The Jazinga system ensures that my voice traffic gets priority on my network so that IP calls are successful. I don’t have to do anything—the system takes care of it.”

One of the reasons Di Nardo chose Jazinga was that it automatically prioritizes the voice traffic on his network. “It shapes your traffic and manages your voice PBX, all in one small appliance,” he explained. “And the call quality is consistently better than all the hosted VoIP solutions that we tried. It’s so easy to use that I can manage it myself, keeping the total cost of ownership low.”

“Customers don’t realize how top-notch their networks need to be to handle VoIP,” says Daniel Song, senior services engineer with Indianapolis-based Interactive Intelligence, which builds call center applications and other business communications solutions. “We noticed that many of our customers were not yet ready for VoIP, so we needed a way to proactively address any potential voice-quality issues before implementing our solutions.”

The company purchased AppCritical from Apparent Networks to test its customers’ networks and to assess call quality before it deployed anything. “AppCritical looks at the end-to-end network path to find problems, such as duplex mismatches, congestion, QoS alterations and bandwidth limitations,” Song explains.

”We are able to diagnose the behavior of the voice packets at each network hop and pinpoint where the problem is occurring. We are also able to verify QoS policies and make sure that service-level agreements are being met.”

And while you are looking at your WAN bandwidth, be sure to examine your network switches, too. “Most companies are going to need a good amount of bandwidth for their internal VoIP network—perhaps 100 Mbps throughout their buildings,” says Joseph Bennett, the IT manager at PTR Baler, a Philadelphia-based industrial company that has been using Alteva VoIP products for about a year.

“But we did need to upgrade our switches to support Power over Ethernet because we wanted to power all our phones from the wiring closets. Even with these upgrades, we are still saving around $2,000 to $3,000 a month on our phone bills, which works out to a nine-month return on the new system.”

3. Do you need any virtual LANs for voice—or some other way to segregate your voice traffic? “We have one vLAN for VoIP internally, and we’ll eventually be using it on 70 phones,” says Tomeu Vidal, IT manager for the city of Campos, Spain, where they have deployed Entrasys switches.

“Many of our customers are setting up segregated voice vLANs or using QoS policies to ensure that voice packets have priority and won’t get dropped,” says Song of Interactive Intelligence. “Part of the problem is being able to understand when the peak call volumes are during the day and making sure you run your assessment during those times to see how many concurrent calls the network can handle while other types of traffic are present.”